An antenna is a transducer that transmits or receives electromagnetic waves. In other words, antennas convert electromagnetic radiation into electrical current, or vice versa. Physically, an antenna is an arrangement of one or more conductors, usually called elements in this context. In transmission, an alternating current is created in the elements by applying a rapidly changing voltage at the antenna terminals, causing the elements to radiate an electromagnetic field. In reception, the inverse occurs: an electromagnetic field from another source induces an alternating current in the elements and a corresponding voltage at the antenna's terminals. Antennas are used in systems such as radio and television broadcasting, point-to-point radio communication, wireless LAN such as WiFi or Bluetooth, cell phones, radar, GPS, remote controls, and spacecraft communication. Technological progress enables new antenna designs that are smaller, have wider bandwidth, and are more conformal. Generally these new designs are significant improvements to the earlier antenna elements.
There are many types of radio antennas: These include: dipole (simply two wires pointed in opposite directions arranged either horizontally or vertically, with one end of each wire connected to the radio and the other end hanging free in space), monopole (half of a dipole antenna, with a ground plane used to reflect a mirror image creating an effective dipole), patch, slot, conformal, spiral, Yagi-Uda (a directional variation of the dipole with parasitic elements added to focus the radiation pattern), horn (used where high gain is needed), parabolic (consists of an active element at the focus of a parabolic reflector to reflect the waves into a plane wave), bow tie, fractal and dielectric resonator antennas. These antenna designs are well known to persons skilled in the radio art.
Composites are engineered or naturally occurring materials made from two or more constituent materials with significantly different physical or chemical properties which remain separate and distinct at the macroscopic or microscopic scale within the finished structure. Composites are made up of individual materials referred to as constituent materials. There are two categories of constituent materials: matrix and reinforcement. At least one portion of each type is required. The matrix material surrounds and supports the reinforcement materials by maintaining their relative positions. The reinforcements impart their special mechanical and physical properties to enhance the matrix properties. A synergism produces material properties unavailable from the individual constituent materials, while the wide variety of matrix and strengthening materials allows the designer of the product or structure to choose an optimum combination. Common composites include woven fibers and a resin matrix to hold the fibers together in a rigid form. Examples of composite reinforcements include fiberglass, Kevlar, and carbon fiber. When mixed with a matrix, generally an epoxy resin, these materials form high strength composites. Other examples of composites are plywood, and the commonly used building material steel-reinforced concrete.
Composites have many uses, such as construction and carpentry. Composite materials are also widely used in ship building, aerospace structures, athletic equipment, high performance cars, storage tanks, vehicles and body armor. Different applications use different variations of a composite. A structural application may use one type of fiberglass weave with a particular resin, while an antenna application uses a different fiberglass weave and a different resin. A protective application may use Kevlar, while carbon fiber is being used in a lot of athletic equipment. One of the many benefits of using a composite is that there are so many possibilities one can design a composite for specific desired properties that may not be readily available.
Armor is a protective covering used to prevent damage from being inflicted to an object, individual or a vehicle through use of direct contact weapons or projectiles, usually during combat, or from damage caused by a potentially dangerous environment or action. Body armor is used by the military and private security to protect personnel from knife and bullet wounds. It generally consists of ceramic or composite plates positioned around the body. Vehicle armor is used to protect a vehicle and its occupants from injury due to impacts and explosions. It has traditionally been solid steel, though ceramics and composites have been used recently.
Land vehicles such as tanks and personnel carriers use armor to protect their occupants and enable completion of their mission. Weight is generally not a significant concern. Aircraft of all forms face similar threats to ground vehicles, but have very strict weight limits. Armor is limited to protecting personnel, and does not cover the whole vehicle. Composites and ceramics are often used due to their lighter weight. Ships and submarines need to limit damage from any explosions.
Armored vehicles typically require multiple antennas covering a broad frequency range for multiple functionalities including communication and sensing. Currently, many of these antennas are extended from the body of the vehicles. These protruding parts of the antennas are vulnerable to attacks, such as gunfire. Antennas become targets for anyone attaching a vehicle, in order to limit their communication abilities, and possibly prevent radio contact about the attack. With large antennas positioned around the vehicle, they are even occasionally shot off by our troops in the heat of battle. To solve this problem, many methods have been proposed including conformal antennas. Antennas which can conform to the surface of vehicles are in great demand for many military applications. Prior art conformal antennas are much less obvious and include antennas embedded in fiberglass or AstroQuartz composite materials, placed on top of the structure of a vehicle or used as the skin of the vehicle. However they are not protected by armor and can be easily damaged by enemy forces.
What is needed is conformal antennas can be embedded into vehicle armor so that the survivability of the antenna is increased greatly.